TRANSLATING TMDLs FOR PERSISTENT POLLUTANTS INTO NPDES PERMIT CONDITIONS: AN UNEASY FIT

Point source dischargers subject to National Pollutant Discharge Elimination System (NPDES) permits are faced with the potentially daunting task of complying with permit conditions that must be consistent with applicable Total Maximum Daily Loads (TMDLs). Wasteload allocations (WLAs) developed as an integral part of a TMDL establish numerical discharge requirements that must be translated into NPDES permit conditions and can result in the imposition of stringent effluent limitations for which treatment technologies may not yet be available. In addition, NPDES permits contain standard conditions, developed over the more than thirty years of the NPDES permit program, that may be incompatible with the requirements of TMDL-driven permit conditions. This paper will evaluate the NPDES permitting process for implementing those aspects of the PCB TMDLs for the Delaware Estuary established by EPA in December, 2003, applicable to point sources dischargers. It will consider both procedural and substantive issues including sampling and reporting protocols, data uncertainties, use of best management practices, compliance deadlines, and the practical dilemmas facing NPDES permit writers.